i had an old farm/heavy equipment shop(holland and sons, no longer around) set up my carb and timing. no where near stock. after a couple of older mech tinkerer's set it up i got about 11 mpg's and a very noticable improvement in power, in an 85 f1504x4 with a c-6, 4.11 gears and 36"s. i was getting about 7-8 before that if i was easy on it, but you're in cali. so unless it's a trailer rig you've got smog f.ing you over. i did go from a holley that was worked over, to a 750 edelbrock performer manual choke/secondaries.